1. Field
A scroll compressor is disclosed herein.
2. Background
In general, a compressor is applicable to a vapor compression type refrigeration cycle (hereinafter, referred to as a “refrigeration cycle”), such as a refrigerator, or an air conditioner, for example. A compressor can be typically divided into a hermetic type compressor, in which an electric motor drive, which is a typical electromotor, and a compression device operated by the electric motor drive are provided together at an inner space of a sealed casing, and an open type compressor, in which the electric motor drive is additionally provided at an outside of the casing. The hermetic compressor is mostly used for household or commercial refrigeration devices.
Further, compressors can be divided into a reciprocating type, a rotary type, or a scroll type, for example, according to a type of compressing of a refrigerant. The reciprocating type compressor is a type that compresses a refrigerant while a piston drive portion linearly moves a piston. The rotary type compressor is a type that compresses a refrigerant using a rolling piston that performs an eccentric rotational movement in a compression space of the cylinder and a vane in contact with the rolling piston to partition the compression space of the cylinder into a suction chamber and a discharge chamber. The scroll compressor is a compressor in which a fixed scroll is fixed to an inner space of the hermetic container, and a plurality of compression chambers including of a suction chamber, an intermediate pressure chamber, and a discharge chamber is consecutively formed between a fixed wrap of the fixed scroll and an orbiting wrap of the orbiting wrap while the orbiting scroll engaged with the fixed scroll performs an orbiting movement. The scroll compressor is widely used for air conditioners, for example, to compress refrigerant due to an advantage of obtaining a relatively high compression ratio compared to the other types of compressors, as well as obtaining a stable torque as suction, compression, and discharge strokes are smoothly carried out.
Furthermore, a compressor can be divided into an upper compression type and a lower compression type according to a location of the electric motor drive and compression device. The upper compression type is a type in which the compression device is located at an upper side of the electric motor drive, and the lower compression type is a type in which the compression device is located at a lower side of the electric motor drive. In particular, in a case of the lower compression type, refrigerant discharged into an internal space of the casing moves to a discharge pipe located at an upper portion of a casing, while oil is recovered to an oil storage space, and thus, there is a concern that oil may be mixed with refrigerant to be discharged out of the compressor or pushed by a pressure of the refrigerant to stagnate at an upper side of the electric motor drive during the process. According to embodiments disclosed herein, a technique in which a passage to recover oil and a passage to discharge a refrigerant may be divided within the casing to reduce oil spill will be described using a high-pressure, lower compression type scroll compressor (hereinafter, referred to as a “lower compression type scroll compressor”) as an example.
FIG. 1 is a cross-sectional view of a lower compression type scroll compressor according to the related art. As illustrated in the drawing, a lower compression type scroll compressor according to the related art may include an electric motor drive 2 provided in an internal space of a casing 1 and having a stator and a rotor, a compression unit or device 3 provided at a lower side of the electric motor drive 2, and a rotational shaft 5 that transmits a rotational force of the electric motor drive 2 to the compression device 3. A refrigerant discharge pipe 16 may be provided at an upper portion of the casing 1.
A passage (Pm) to guide oil separated from refrigerant at an upper side space of the electric motor drive 2 to be recovered to an oil storage space (V3) at an upper side space of the electric motor drive 2 at a lower side of the compression device 3 while at the same time guiding refrigerant discharged from the compression device 3 to move in a direction of the refrigerant discharge pipe 16 may be formed on an inner circumferential surface of the casing 1 and an outer circumferential surface of the electric motor drive 2 or an inner portion of the electric motor drive 2.
According to the foregoing lower compression type scroll compressor according to the related art, refrigerant and oil discharged from the compression device 3 may move to an upper side of the electric motor drive 2 through the passage (Pm) provided in the electric motor drive 2, and then, may be discharged to an outside of the compressor through the refrigerant discharge pipe 16. At the same time, oil separated from refrigerant between the electric motor drive 2 and the compression device 3 may move to the oil storage space (V3) through a passage (Pc) provided in the compression device 3, while oil separated from refrigerant at the upper side of the electric motor drive 2 may moves to the oil storage space (V3) at the lower side of the compressor through the passage (Pm) provided in the electric motor drive 2 and the passage (Pc) provided in the compression device 3.
Discharge refrigerant discharged into the internal space of the casing 1 from the compression device 3 may include oil. Recovery of oil contained in the discharged refrigerant is a key factor for system efficiency and compressor reliability.
For the upper compression type scroll compressor, the compression device may be located at an upper side of the casing, and thus, refrigerant coming out of the compression device may be almost directly discharged through the refrigerant discharge pipe, and has a short period of discharge time, thus resulting in a low oil separation efficiency. In contrast, for the lower compression type scroll compressor, the compression device 3 is located at the lower side of the casing 1, and thus, refrigerant coming out of the compression device 3 passes through other spaces to be discharged through the refrigerant discharge pipe 16, and thus, there is a sufficient time for oil to be separated therefrom before the discharge time, thus resulting in a relatively high oil separation efficiency.
Oil in the oil storage space (V3) may be supplied to the compression device 3, and oil remaining after lubricating the compression device 3 and oil mixed with compressed refrigerant may be accumulated on an upper surface of the compression device 3. As a result, the supply of oil to the compression device 3 may not be efficiently carried out in the oil storage space (V3) due to the shortage of oil, thereby causing damage to the compression device 3 or the rotational shaft 5.
Accordingly, the oil accumulated on an upper surface of the compression device 3 should be guided to the oil storage space (V3) at a bottom portion thereof in order to supply oil to the compression device 3. The recovery of oil to the oil storage space (V3) is very important to of the reliability of the compressor.
However, a wide oil discharge path should be provided to efficiently recover oil, but if the oil discharge path is too wide, then a fixed area for the casing of the main frame may decrease, deteriorating a fixing strength of the main frame. As a result, the oil discharge path should be formed to provide a sufficient fixed area.